sys: Correct types of sys.displayhook, sys.excepthook and variants (#3673)

displayhook should accept any object, not just integers.

displayhook and excepthook may be assigned to, so they should be
Callable values rather than function definitions. That way it's fine
to assign a function with different argument names. Their dunder
variants are supposed to be constant.

stdlib/2/sys.pyi

@@ -89,8 +89,8 @@ last_traceback: TracebackType
 meta_path: List[Any]
 path_hooks: List[Any]
 path_importer_cache: Dict[str, Any]
-displayhook: Optional[Callable[[int], None]]
-excepthook: Optional[Callable[[type, BaseException, TracebackType], None]]
+displayhook: Callable[[object], Any]
+excepthook: Callable[[Type[BaseException], BaseException, TracebackType], Any]
 exc_type: Optional[type]
 exc_value: Union[BaseException, ClassType]
 exc_traceback: TracebackType
@@ -112,7 +112,7 @@ def _clear_type_cache() -> None: ...
 def _current_frames() -> Dict[int, FrameType]: ...
 def _getframe(depth: int = ...) -> FrameType: ...
 def call_tracing(fn: Any, args: Any) -> Any: ...
-def __displayhook__(value: int) -> None: ...
+def __displayhook__(value: object) -> None: ...
 def __excepthook__(type_: type, value: BaseException, traceback: TracebackType) -> None: ...
 def exc_clear() -> None: ...
 def exc_info() -> _OptExcInfo: ...